It is common for an owner of a vehicle, such as an automobile, truck or the like, to tow or trail various trailers, such as a camper trailer, a boat trailer, a storage trailer, or the like. Electrical power is made available to the trailer by an electrical connector that electrically connects the towing vehicle's electrical supply system to a trailer electrical system. Vehicle electrical connectors can be configured to connect between the various trailers and the vehicle. For example, the Society of Automotive Engineers (SAE) has promulgated a standardized connection scheme that allows for intermixed connection between various types of vehicles and trailers.
In some vehicles, a standardized connection scheme includes an output for providing current to an auxiliary power source such as a battery of the trailer. When the trailer is connected to the vehicle, a vehicle battery charges the trailer battery via the output of the electrical connector. When charged, the trailer battery supplies power to various electrical loads of the trailer.
In some cases, current can flow from the trailer back to the vehicle when the voltage of the trailer battery is higher than the voltage of the vehicle battery. Such is typically the case during a vehicle cranking event. When the trailer battery is fully charged, the reverse current flow can be excessive and can cause damage to electronic switching components of the electrical connection. To prevent this damage, an additional switch, such as a relay contactor or a second field effect transistor (FET) can be used to block the reverse current flowing to the vehicle. For example, one switch is controlled to allow current to flow from the vehicle to the trailer and the other is controlled to block current flowing from the trailer to the vehicle. However, implementing two switches may introduce additional costs as well as complexity to the vehicle electrical connection system.